Energy pipeline operator Enbridge has pulled employees from several offshore U.S. Gulf of Mexico platforms, the company told customers, as Tropical Storm Francine advanced toward a landfall in Louisiana.

Francine has shut in oil and gas production at offshore platforms operated by Chevron, Exxon Mobil and Shell. The first official measure of the storm's impact on U.S. energy production will be released later on Tuesday by U.S. regulator the Bureau of Safety and Environmental Enforcement.

Enbridge, which manages an extensive network of offshore pipelines funneling oil and gas to onshore plants, evacuated staff from three offshore platforms. Operations are continuing at each using remote operators, it said in notices to customers.

Staff were removed from South Marsh Island 76, Ship Shoal 207 and 332 platforms, the customer notices said. South Marsh Island 76 connects a 1 billion cubic feet per day natural gas offshore pipeline. 

The Manta Ray Gas Gathering system declared force majeure at its Green Canyon 158 Brutus receipt point and stopped receiving natural gas, Enbridge told customers.

Force majeure is a provision that allows a contract to be suspended due to unforeseen events. The receipt point would be returned to service once the company can replace a malfunctioning valve, Enbridge said.